Circuit board, method for making the same, and portable electronic device employing the same

ABSTRACT

A circuit board includes a core layer, at least one passive component, a first and a second conductive wire layers, at least one contact pad, and a resin packing layer. The core layer defines at least one through hole to receive the passive component. The first and the second conductive wire layers are connected to two opposite surfaces of the core layer. Each contact pad is positioned between and connected to one passive component and the first conductive wire layer. The resin packing layer is filled among the core layer, each passive component, each contact pad, the first and the second conductive wire layers. The resin packing layer can connect the first and the second conductive wire layers to the core layer, and connect the core layer, each passive component, and each contact pads to each other.

FIELD

The subject matter herein generally relates to a circuit board, a methodfor making the circuit board, and a portable electronic device employingthe circuit board.

BACKGROUND

Many portable electronic devices, such as cell phones, tablet computers,or multimedia players, usually include circuit boards. Passivecomponents of a circuit board, such as resistors or capacitors, areusually embedded in a substrate of the circuit board in order todecrease the thickness of the portable electronic device. Duringmanufacturing, the passive components are disposed between two resinlayers, and the two resin layers are pressed and connected to eachother, thereby embedding the passive components in the two resin layers.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present technology will now be described, by wayof example only, with reference to the attached figures.

FIG. 1 is a diagrammatic view of an embodiment of a circuit boardaccording to the present disclosure.

FIG. 2 is a flowchart of an embodiment of a method for making a circuitboard according to the present disclosure.

FIG. 3 is a diagrammatic view of a supporting plate comprising asupporting portion and two first copper layers connected to thesupporting portion used in the method of FIG. 2.

FIG. 4 is a diagrammatic view showing an electro-plating layer beingformed on the supporting plate of FIG. 3.

FIG. 5 is a diagrammatic view showing a conductive paste layer beingformed on the supporting plate of FIG. 3.

FIG. 6 is a diagrammatic view showing at least one passive component andat least one contact pad being formed on the conductive paste layer ofFIG. 5.

FIG. 7 is a diagrammatic view showing a first resin layer being formedon the first copper layer of FIG. 6.

FIG. 8 is a diagrammatic view showing a core layer, a second resinlayer, and a second copper layer being formed on the first resin layerof FIG. 7.

FIG. 9 is a diagrammatic view of a first intermediate product formed bypressing the first copper layer, the first resin layer, the core layer,the passive component, the contact pad, the second resin layer, and thesecond copper layer of FIG. 8.

FIG. 10 is a diagrammatic view of two second intermediate productsformed by removing the supporting plate of FIG. 9.

FIG. 11 is a diagrammatic view of a first conductive wire layer and asecond conductive wire layer being formed by the first copper layer andthe second copper layer included in one second intermediate product ofFIG. 10.

FIG. 12 is a diagrammatic view of a portable electronic device includingthe circuit board of FIG. 1.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures, and components havenot been described in detail so as not to obscure the related relevantfeature being described. Also, the description is not to be consideredas limiting the scope of the embodiments described herein. The drawingsare not necessarily to scale and the proportions of certain parts may beexaggerated to better illustrate details and features of the presentdisclosure.

The term “comprising,” when utilized, means “including, but notnecessarily limited to”; it specifically indicates open-ended inclusionor membership in the so-described combination, group, series and thelike.

FIG. 1 illustrates an embodiment of a circuit board 100 comprising acore layer 50, at least one passive component 30, a first conductivewire layer 91, a second conductive wire layer 92, at least one contactpad 20, and two solder mask layers 101. The core layer 50 defines atleast one through hole 51, and comprises a first surface and a secondsurface opposite to the first surface. Each passive component 30 isreceived in one through hole 51. The first conductive wire layer 91 andthe second conductive wire layer 92 are respectively connected to thefirst surface and the second surface of the core layer 50. Each contactpad 20 is positioned between and connected to one passive component 30and the first conductive wire layer 91. One solder mask layer 101 isconnected to a surface of the first conductive wire layer 91 away fromthe core layer 50. The other solder mask layer 101 is connected to asurface of the second conductive wire layer 92 away from the core layer50. The at least one passive component 30 may be a resistor, acapacitor, or an inductance.

The circuit board 100 further comprises a resin packing layer 80 filledin among the core layer 50, the at least one passive component 30, theat least one contact pad 20, the first conductive wire layer 91, and thesecond conductive wire layer 92. The resin packing layer 80 isconfigured to connect the first conductive wire layer 91 and the secondconductive wire layer 92 to the first and the second surfaces of thecore layer 50. The resin packing layer 80 is further configured toconnect the core layer 50, the at least one passive component 30, andthe at least one contact pad 20 to each other. The at least one contactpad 20 is configured to connect the at least one passive component 30 tothe first conductive wire layer 91, thereby preventing the at least onepassive component 30 from being moved during a manufacturing process ofthe circuit board 100.

Each of the at least one contact pad 20 is made of conductive material.In at least one embodiment, each of the at least one contact pad 20comprises an electro-plating layer 21 connected to the first conductivewire layer 91 and a conductive paste layer 22 positioned between andconnected to one of the at least one passive component 30 and theelectro-plating layer 21. The electro-plating layer 21 is made of copperor aluminum. The conductive paste layer 22 is made of conductive pasteconsisting of conductive powder (or silver powder) and lipids. Inanother embodiment, the conductive paste layer 22 may be omitted. The atleast one passive component 30 is connected to the at least one contactpad 20 via a solder (not shown). In yet another embodiment, theelectro-plating layer 21 may be omitted.

The resin packing layer 80 is made of an adhesive resin composition. Theadhesive resin composition comprises adhesive resin selected from agroup consisting of polypropylene (PP), epoxy resin, polyurethane (PU),phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin,and polyimide, or any combination thereof.

The first conductive wire layer 91 and the second conductive wire layer92 are made of copper. Each of the first conductive wire layer 91 andthe second conductive wire layer 92 comprises a number of conductiveportions 93 protruding towards the core layer 50. The first conductivewire layer 91 and the second conductive wire layer 92 are electricallyconnected to the core layer 50 via the conductive portions 93. In atleast one embodiment, a number of plating holes 81 are defined through aportion of the resin packing layer 80. Each conductive portion 93 isformed in one plating hole 81, thereby causing the first conductive wirelayer 91 and the second conductive wire layer 92 to be electricallyconnected to the core layer 50 via the conductive portion 93. In atleast one embodiment, the conductive portion 93 is made of copper oraluminum.

Each solder mask layer 101 is made of liquid photoimageable material. Anumber of openings 1010 are defined in each solder mask layer 101.Portions of the first conductive wire layer 91 and portions of thesecond conductive wire layer 92 are exposed via the openings 1010,thereby allowing the first conductive wire layer 91 and the secondconductive wire layer 92 to be electrically connected to externalelectric components (not shown).

In other embodiments, the circuit board 100 may further comprise a fewmore conductive wire layers (not shown) connected to each of the firstconductive wire layer 91 and the second conductive wire layer 92 andfacing away from the core layer 50. The solder mask layer 101 isconnected to an exterior one of the conductive wire layers.

Referring to FIG. 2, a flowchart for making the circuit board 100 ispresented in accordance with an example embodiment which is being thusillustrated. The example method for making the circuit board 100 isprovided by way of example, as there are a variety of ways to carry outthe method. The method described below can be carried out using theconfigurations illustrated in FIG. 1, for example, and various elementsof these figures are referenced in explaining the example method. Eachblock shown in FIG. 2 represents one or more processes, methods orsubroutines, carried out in the exemplary method. Furthermore, theillustrated order of blocks is by example only and the order of theblocks can change according to the present disclosure. Additional blocksmay be added or fewer blocks may be utilized, without departing fromthis disclosure. The exemplary method can begin at block 21.

At block 21, a supporting plate 200 (shown in FIG. 3) is provided. Thesupporting plate 200 comprises a supporting portion 201 and two firstcopper layers 10. The two first copper layers 10 are respectivelyconnected to two opposite surfaces of the supporting portion 201.

At block 22, at least one contact pad 20 (FIGS. 4 and 5) is connected toa surface of each first copper layer 10 away from the supporting portion201. In at least one embodiment, an electro-plating layer 21 (shown inFIG. 4) is formed on the surface of the first copper layer 10 byelectro-plating, and a conductive paste layer 22 (shown in FIG. 5) isformed on a surface of the electro-plating layer 21 away from the firstcopper layer 10 by coating a conductive paste (not shown), therebyforming the contact pad 22 comprising the electro-plating layer 21 andthe conductive paste layer 22. In another embodiment, an electro-platinglayer 21 is formed on the surface of the first copper layer 10, therebyforming the contact pad 20 only comprising the electro-plating layer 21.In yet another embodiment, a conductive paste layer 22 is formed on thesurface of the first copper layer 10, thereby forming the contact pad 20only comprising the conductive paste layer 22.

At block 23, at least one passive component 30 (shown in FIG. 6) isconnected to a surface of the contact pad 20 away from the first copperlayer 10. When the contact pad 20 comprises the electro-plating layer 21and the conductive paste layer 22, the passive component 30 is connectedto the conductive paste layer 22. When the contact pad 20 only comprisesthe electro-plating layer 21, the passive component 30 is directlyconnected to the contact pad 20 via a solder paste (not shown). When thecontact pad 20 only comprises the conductive paste layer 22, the passivecomponent 30 is directly connected to the conductive paste layer 22.

At block 24, a first resin layer 40 (shown in FIG. 7) is formed on aportion of each first copper layer 10 besides the passive component 30.The first resin layer 40 is made of an adhesive resin composition. Theadhesive resin composition comprises adhesive resin selected from agroup consisting of PP, PU, phenolic resin, urea-formaldehyde resin,melamine-formaldehyde resin, and polyimide, or any combination thereof.

At block 25, a core layer 50 (shown in FIG. 8) defining at least onethrough hole 51 is disposed on a surface of each first resin layer 40away from the first copper layer 10 to allow the passive component 30 tobe received in the through hole 51, and a second resin layer 60 and asecond copper layer 70 are successively disposed on each core layer 50and the passive component 30. The second resin layer 60 is made of anadhesive resin composition. The adhesive resin composition comprisesadhesive resin selected from a group consisting of PP, PU, phenolicresin, urea-formaldehyde resin, melamine-formaldehyde resin, andpolyimide, or any combination thereof. The adhesive resin composition ofthe second resin layer 60 may be the same as that of the first resinlayer 40.

At block 26, the two second copper layer 70 (shown in FIG. 9) arepressed, thereby causing the supporting portion 201, the first copperlayer 10, the contact pad 20, the passive component 30, the first resinlayer 40, the core layer 50, the second resin layer 60, and the secondcopper layer 70 to be connected to each other to form a firstintermediate product 300. In at least one embodiment, the adhesive resincomposition of the first resin layer 40 and the second resin layer 60flows to fill gaps between the first copper layer 10, the contact pad20, the passive component 30, the core layer 50, and the second copperlayer 70, thereby causing the first resin layer 40 and the second resinlayer 60 to be connected to each other to from the resin packing layer80. Since the passive component 30 is connected to the contact pad 20,the passive component 30 cannot move when the two second copper layers70 are pressed. Furthermore, the pressing of the second copper layers 70may prevent bubbles from being generated in the resin packing layer 80.

At block 27, the supporting portion 201 of the first intermediateproduct 300 (shown in FIG. 10) is removed to form two separate secondintermediate products 400.

At block 28, a number of plating holes 81 (shown in FIG. 11) are definedon a portion of the first copper layer 10 and the second copper layer70, and a corresponding portion of the resin packing layer 80 includedin each second intermediate product 400, and a conductive portion 93 isformed in each plating hole 81 which is electrically connected to thefirst copper layer 10, the second copper layer 70, and the core layer50. The first copper layer 10 and the second copper layer 70 are furtheretched to form conductive wires, thereby forming the first conductivewire layer 91 and the second conductive wire layer 92, respectively. Thefirst conductive wire layer 91 and the second conductive wire layer 92are electrically connected to the core layer 50 via the conductiveportions 93.

At block 29, the solder mask layer 101 is connected to a surface of eachof the first conductive wire layer 91 and the second conductive wirelayer 92 away from the core layer 50, and a number of openings 1010 aredefined in each solder mask layer 101 to form the circuit board 100.

In other embodiments, a number of conductive wire layers (not shown) maybe connected to a surface of each of the first conductive wire layer 91and the second conductive wire layer 92 away from the core layer 50 by abuild-up method, thereby forming a circuit board 100 comprising a numberof conductive wire layers (not shown).

It is noteworthy that although the supporting plate 200 comprising twofirst copper layers 10 are used to obtain two second intermediateproducts 400, in other embodiments, a supporting plate 200 comprisingonly one first copper layer 10 can also be used. In this embodiment,only one second intermediate product 400 is obtained.

FIG. 12 illustrates a portable electronic device 500 comprising thecircuit board 100. The portable electronic device 500 further comprisesa casing 501, a display screen 502 mounted to the casing 501, and areceiving space (not shown) cooperatively defined by the casing 501 andthe display screen 502. The circuit board 100 is fixedly received in thereceiving space.

It is to be understood, even though information and advantages of thepresent embodiments have been set forth in the foregoing description,together with details of the structures and functions of the presentembodiments, the disclosure is illustrative only; changes may be made indetail, especially in matters of shape, size, and arrangement of partswithin the principles of the present embodiments to the full extentindicated by the plain meaning of the terms in which the appended claimsare expressed.

What is claimed is:
 1. A circuit board comprising: a core layer definingat least one through hole and having a first surface and a secondsurface opposite the first surface; at least one passive component eachbeing received in the through hole; a first conductive wire layerconnected to the first surface; a second conductive wire layer connectedto the second surface; at least one contact pad each positioned betweenone of the at least one passive component and the first conductive wirelayer, and electrically connected to the one passive component and thefirst conductive wire layer; and a resin packing layer filled in amongthe core layer, each of the at least one passive component, each of theat least one contact pad, the first conductive wire layer, and thesecond conductive wire layer and connecting the first conductive wirelayer and the second conductive wire layer to the first and secondsurfaces of the core layer, wherein the resin packing layer furtherconnects the core layer, each of the at least one passive component, andeach of the at least one contact pad to each other.
 2. The circuit boardof claim 1, wherein each of the at least one contact pad comprises anelectro-plating layer connected to the first conductive wire layer and aconductive paste layer positioned between and connected to the passivecomponent and the electro-plating layer.
 3. The circuit board of claim2, wherein the electro-plating layer is made of copper or aluminum; theconductive paste layer is made of conductive paste consisting ofconductive powder and lipids.
 4. The circuit board of claim 1, whereineach of the first conductive wire layer and the second conductive wirelayer comprises a plurality of conductive portions protruding towardsthe core layer; the first conductive wire layer and the secondconductive wire layer are electrically connected to the core layer viathe conductive portions.
 5. The circuit board of claim 4, wherein aplurality of plating holes are defined on a portion of the resin packinglayer; each conductive portion is received in one of the plurality ofplating holes, thereby causing the first conductive wire layer and thesecond conductive wire layer to be electrically connected to the corelayer via the conductive portion.
 6. The circuit board of claim 1,wherein the resin packing layer is made of an adhesive resincomposition; the adhesive resin composition comprises adhesive resinselected from a group consisting of polypropylene, polyurethane,phenolic resin, urea-formaldehyde resin, melamine-formaldehyde resin,and polyimide, or any combination thereof.
 7. The circuit board of claim1, further comprising two solder mask layers, wherein one solder masklayer is connected to a surface of the first conductive wire layer awayfrom the core layer; the other solder mask layer is connected to asurface of the second conductive wire layer away from the core layer. 8.The circuit board of claim 7, wherein a plurality of openings aredefined in each of the two solder mask layer; portions of the firstconductive wire layer and portions of the second conductive wire layerare exposed via the plurality of openings.
 9. A method for making acircuit board comprising: providing a supporting plate comprising asupporting portion and at least one first copper layer connected to atleast one surface of the supporting portion; connecting at least onecontact pad to a surface of each of the at least one first copper layeraway from the supporting portion; connecting at least one passivecomponent to a surface of each of the at least one contact pad away fromthe first copper layer; forming a first resin layer on a portion of eachof the at least one first copper layer besides the passive component;disposing a core layer defining at least one through hole on a surfaceof each first resin layer away from the first copper layer to allow thepassive component to be received in the through hole, and disposing asecond resin layer and a second copper layer successively on each corelayer and the passive component; pressing the two second copper layercausing the supporting portion, the first copper layer, the contact pad,the passive component, the first resin layer, the core layer, the secondresin layer, and the second copper layer to be connected to each otherto form a first intermediate product, wherein the first resin layer andthe second resin layer flows to fill gaps between the first copperlayer, the contact pad, the passive component, the core layer, and thesecond copper layer, thereby connecting to each other to from a resinpacking layer; removing the supporting portion of the first intermediateproduct to form at least one second intermediate product; and etchingthe first copper layer and the second copper layer to form a firstconductive wire layer and a second conductive wire layer.
 10. The methodof claim 9, wherein before the step of “etching the first copper layerand the second copper layer to form a first conductive wire layer and asecond conductive wire layer” further comprises: defining a plurality ofplating holes at a portion of the first copper layer and the secondcopper layer, and a corresponding portion of the resin packing layercomprised in each of the at least one second intermediate product; andforming a conductive portion in each of the plurality of plating holeswhich is electrically connected to the first copper layer, the secondcopper layer, and the core layer.
 11. The method of claim 9, whereinafter the step of “etching the first copper layer and the second copperlayer to form a first conductive wire layer and a second conductive wirelayer” further comprises: connecting a solder mask layer to a surface ofeach of the first conductive wire layer and the second conductive wirelayer away from the core layer; and defining a plurality of openings ateach solder mask layer.
 12. The method of claim 9, wherein the step of“connecting at least one contact pad to a surface of each of the atleast one first copper layer away from the supporting portion” furthercomprises: forming an electro-plating layer on the surface of the firstcopper layer by electro-plating; and forming a conductive paste layer ona surface of the electro-plating layer away from the first copper layerby coating a conductive paste, thereby forming the contact padcomprising the electro-plating layer and the conductive paste layer. 13.The method of claim 9, wherein the first resin layer is made of anadhesive resin composition; the adhesive resin composition comprisesadhesive resin selected from a group consisting of polypropylene,polyurethane, phenolic resin, urea-formaldehyde resin,melamine-formaldehyde resin, and polyimide, or any combination thereof.14. The method of claim 9, wherein the second resin layer is made of anadhesive resin composition; the adhesive resin composition comprisesadhesive resin selected from a group consisting of polypropylene,polyurethane, phenolic resin, urea-formaldehyde resin,melamine-formaldehyde resin, and polyimide, or any combination thereof.15. A portable electronic device comprising: a circuit board comprising:a core layer defining at least one through hole and having a firstsurface and a second surface opposite the first surface; at least onepassive component each being received in one through hole; a firstconductive wire layer connected to the first surface; a secondconductive wire layer connected to the second surface; at least onecontact pad each positioned between one of the at least one passivecomponent and the first conductive wire layer, and electricallyconnected to the one passive component and the first conductive wirelayer; and a resin packing layer filled in among the core layer, each ofthe at least one passive component, each of the at least one contactpad, the first conductive wire layer, and the second conductive wirelayer and connecting the first conductive wire layer and the secondconductive wire layer to the first and second surfaces of the corelayer, wherein the resin packing layer further connects the core layer,each of the at least one passive component, and each of the at least onecontact pad to each other.